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SUMMARY:"Wnt signaling and stem cell control" by Prof. Roel Nusse
DTSTART:20090917T160000
DTSTAMP:20260530T194013Z
UID:03e21feca86f495e46fd33a832b45e92f86b01b45651767e6c110ad8
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Roel Nusse\, Department of Developmental Biology and How
 ard Hughes Medical Institute\, Stanford University\, USA \nAbstract  In ma
 ny contexts\, the self-renewal and differentiation of stem cells is influe
 nced by signals from their environment\, constituting a niche. It is postu
 lated that stem cells compete for local growth factors in the niche\, ther
 eby maintaining a balance between the numbers of self-renewing and differe
 ntiated cells. A critical aspect of the niche model for stem cell regulati
 on is that the availability of self-renewing factors is limited and that s
 tem cells compete for these factors. Consequently\, the expression\, range
  and concentrations of the niche factors are critical importance.   We stu
 dy the role of Wnt signaling and stem cells by purifying active Wnt protei
 ns and applying them to cells and tissues\, thereby being able to assess t
 he consequences of Wnt signaling in a direct way. Wnt proteins are modifie
 d by lipid attachment\, to make them hydrophobic in nature. We found that 
 isolated Wnt proteins are active on a variety of stem cells\, including ne
 ural\, mammary and embryonic stem cells. In general\, Wnt proteins act to 
 maintain the undifferentiated state of stem cells\, while other growth fac
 tors instruct the cells to proliferate. The combination of Wnts and those 
 factors has allowed is to clonally expand and propagate stem cells in an u
 ndifferentiated state for multiple passages. By subsequent in vivo transpl
 antation\, we find that the cells have retained their developmental potent
 ial.   During the diffusion and transport of the lipid-modified Wnt protei
 ns between cells\, the interaction with a novel Wnt binding protein\, call
 ed SWIM\, may be essential in maintaining the solubility of Wnt\, at least
  in Drosophila.
LOCATION:SG 0 211
STATUS:CONFIRMED
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